Immortality: Not Just For Alicorns

With the ongoing agreement in the fandom about alicorns and immortality I decided to add my own opinion on the matter. My opinion yes and no. I believe that being born an alicorn doesn't automatically make you immortal, it has to be earned. This is also true for nonalicorns as well.
The is evidence for this theory starts with The Mysterious Mare Do Well. When Mare Do Well is fixing the dam and showing her magic and flight skills, the townsponies show no shock at the fact that Mare Do Well is an alicorn. This hints that being born an alicorn is nothing special.
More evidence is in Rarity Takes Manehattan. While trying to call a taxi no one notices that Twilight is an alicorn. It could show that the ponies of Manehattan don't see alicorns as anything special.
Now the question remains how do alicorns become immortal? I believe that they gain it through doing something extraordinary. For Celestia and Luna it could either being their ability to raise the sun and moon or their former contention to the Elements of Harmony. Cadence got hers by her ability to spread love to everypony. Twilight received hers by being the Element of Magic. This is also true for the other members mane six.
That's right the main six are immortal too. I also believe anyone who does something extraordinary can become immortal too.
An example of a nonalicorn with immortality is Discord. Discord is the spirit of chaos, so as long as there's chaos, Discord will live on. Shining Armor is also a nonalicorn with immortality. He received his by marrying Cadence. Finally the mane have their's through their connection with the Elements of Harmony and now Rainbow Power.